Rolling mill



'Nov. 3, 1931.

, F. ,KOVCKS ROLLING MILL Filed Dec. 14. 1929 Patented Nov. 3, 1931 UNITED STATES PATENT; OFFICE I i Irma xocxs, or nnssnnnoar, exam I i Application fled December 14, 1929, Serial No. 414,188, and in Germany larch 7, 1929.

My invention relates to rolling mills and more especially to mills on which blanks are expanded. It has articular reference to a rolling mill which 15 adapted for the carrying out of the process described in my copending application for patent, Ser. No. 343,7 81, filed February 15, 1929, which comprises imparting to the blank equal feed velocity at all points of contact between the rollers and the blank.

It is an object of my invention to improve the rollin mill by which the aforesaid process is carried out. To this end I arrange the axes of the rolls of the mill at an angle to the axis of the blank which does not exceed 30 egs.

It has been found that a mill of the kind referred to is improved by inclining the axes of the rolls at a comparatively small angle to the axis of the blank, as is'shown but not claimed in the copending application.

In mills of this type the inclination of the axes of the rolls is large, and as a rule the angle which according to the present invention must not exceed degs., is about 60 de Rolls the axes of which are inclined to t e blank at such a large angle are of a very markeddaper and short in pro ortion so that in fact they are flat discs. orresponding to the taper of the rolls, the ta er of the mandrel is also-very marked, an its face'is as short'as are the faces of the-rolls.

With the axes of the rolls inclined at this large angle, it is diflicult to accommodate the driving mechanism and therefore mills of the type referred to could only be equipped with two rolls and required guiding means the provision of which involves further difficulties.

' These drawbacks are overcome according to my invention by reducing the angle which the axes of the ro ls include with the axis of the blank. The maximum angle at which the axes of the rolls should be inclined is 30 degs., and a favorable angle is about 15 'degs.

In a, mill of this type the rolls have a slight taper only and'are very long in consequence. The mandrel is long and slightly tapers in accordance with the rolls. Rolls of this kind can be supported in bearings at either end andthere is no difiiculty to accommodate the driving mechanism so that three rolls may be rovided instead of two, if desired.

ne of the advantages obtained by a mill of this kind is that the forging of the blank is much more favorable with respect to the expanding process. The very long and slightly tapering rolls in cooperation with a mandrel havingj the same properties, act on the blank with surfaces which are as long as the rolls and the mandrel, but ver narrow in the direction in which the rol s rotate. Such lon and narrow surfaces practically forge the. lank exclusively at right angles to 7 this longitudinal dimension. he forging 5 surfaces rather resemble those of sheet-metal rolls. It is known that in such rolls there occurs no deformation in parallel relation to the longitudinal dimension of the forging surface. -In the present instance longitudinal expansion of the material in the axial direction of the tube is practically eliminated which is favorable with respect to the expansion of the tube and in connection with the process described in my copending applica tion.

Another very important advantage of my rolling mill with its slightly inclined rolls is that the feed-velocity can be considerably increased as compared with the rolling mills hitherto designed. The time required for rolling a tube is a fraction of the time at present required which not only increases the output 0 the mill but also makes it comparatively independent from the radual cooling of the blank. The explanation is that in a rolling mill according to my invention, as compared with a mill of the type referred to, the section of the blank which is being forged at a time, is much larger. The effect is simi-l 9 lar to that obtained by sub-dividing the last stages of a small-section rollingmill in order to increase the output of the mill. In the mill according to my invention the length of tube which is being forged is increased, thereby also increasing the feed and the output. The possibility of practically eliminating the temperature factor removes a serious drawback inherent in thepresent system, to wit, its long rolling periods. The consequence of these long periods was that the temperature at the end of the tube, which was forged toward the close of the process, was much lower than the initial temperature, which in turn caused irregularities in the wall thickness and the outside diameter, and, under certain conditions, even rendered the process impracticable. In my improved mill the relation of the feeding and rotary components of the circumferential velocity of the rolls is different from that in normal rolls.

This relation or, in other words, the direction of the circumferential velocity, is a function of the distance between a given point of contact and the axis of the system, and the feedingcomponent is increased by reducing this distance.

The advantage of providing bearings at either end of the rolls is obvious, and the possibility of providing three rolls eliminates the necessity of providing guiding means,- while an absolutely reliable centering of the mandrel and a thoroughly uniform for g of the material by all rolls is guarantee" In the drawings aflixed to this specification and forming part thereof a rolling mill embodying my invention is illustrated diagrammatically by way of example.

In the drawings Fig. 1 is a plan view, and

Figs. 2 and 3 are sections on the lines II II, and III-]II in Fig. 1, respectively.

Referring now to the drawmgs, p are the three rolls the axes of which are 1nclined to the axis of the blank at an angle not exceeding 30 degs. Each roll is supported in the housings a and b by means of spherical bearings {and g, respectively, 0 are s' indles from whic the rolls are driven by sultable knuckles d. 0 are foundations on which the hous- .the reception of the blank and the finished tube, respectively.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

I claim: A rolling mill for the expanding of blanks comprising long slightly tapered rolls, two bearings in and between which said rolls are 

